1. Field of the Invention
The present invention relates generally to a printed circuit board and a routing scenario thereof, and more particularly to a printed circuit board and an interleaving routing scenario thereof for reducing the crosstalk between signal traces in the printed circuit board, and for saving the routing real estate.
2. Prior Art
The advancement of electronic industry demands more and more electronic components to be integrated on a single printed circuit board. Besides, smaller and smaller size of the printed circuit board is in need for smaller and smaller electronic products. As a result, a printed circuit board with a limited area requires disposing denser and denser routing scenario thereon. This narrows the spacing between signal traces.
Conventionally, a printed circuit board adopts a right-angle routing scenario, a 45 degrees routing scenario, a differential routing scenario or a zigzag routing scenario. In applications of high-speed design, one usually employs the differential routing scenario.
Referring to FIG. 1, the differential routing scenario of the conventional printed circuit board in stripline geometry is illustrated. As shown, the printed circuit board 100 comprises a first ground plate 110, a first dielectric layer 120, a signal layer 130, a second dielectric layer 140, and a second ground plate 150, wherein a plurality of differential pairs, such as a first differential pair 131 and a second differential pair 134, is disposed within the signal layer 130. The signal layer 130 is formed between the first dielectric layer 120 and the second dielectric layer 140. The first ground plate 110 is formed above the first dielectric layer 120, while the second ground plate 150 is formed beneath the second dielectric layer 140. The first dielectric layer 120 and the second dielectric layer 140 is made of either a homogeneous dielectric material or a non-homogeneous dielectric material. Data signals on the first differential pair 131 and the first differential pair 134 are directed and flowed to the same direction.
However, the conventional differential routing scenario, illustrated in FIG. 1, is disadvantageous in that the differential pairs are dispose layer. The denser the differential pairs are disposed in the same signal layer, the higher the crosstalk between differential pairs is increased. Besides, the denser the differential pairs are disposed in the same signal layer, the more likely the electromagnetic interference between differential pairs would incur. These would largely reduce the performance of the entire printed circuit board system. Therefore, there is a need for a differential routing scenario that may prevent the crosstalk and the electromagnetic interference between differential pairs from happening.